The invention relates to an electrically heated cutting tool for cutting rubber and plastics, the tool comprising a blade of flat material through which current flows, the blade being substantially U-shaped and having two limbs, the free ends of which are connected with the two poles of a power supply. In a known tool of this art (German Pat. No. 1 943 189) the knife takes the form of a flat blade the limbs of which end in the connecting region, i.e. in the region where the limbs are connected together, in a V-shaped or acute angled cutting edge. A cutting tool of this kind makes it possible to cut rubber and plastics without waste so long as the location of the cut and/or the line along which the cut is to be made are freely accessible. For cutting locations which are difficult to reach, for example when cutting adhesively secured panes for vehicles, the use of the known blade is difficult if not indeed impossible.